1. Field of the Invention
This invention relates to apparatus for limiting the distance a door can be opened farther from a completely shut position or a partly opened position.
2. Description of the Prior Art
Many devices have been proposed for keeping doors closed against unwanted intrusion. Perhaps the earliest of these devices is a simple bar which drops into upwardly opening brackets secured to the door frame on opposite sides of the door. While the bar is quite effective in keeping the door shut, it must be lifted from its supporting brackets in order to open the door at all, even an inch or two. This makes it difficult for the person inside the room to ascertain who, if anyone, is on the other side of the door before removing the bar. Fish eye lenses are only partially successful, and do not permit the door to be opened only an inch or two for speaking through the door or for passing papers and the like from the outside to the inside or vice versa. Moreover, most door frames are relatively flimsy and even a barred door can often be forced open by a sharp kick or slamming a person's body against the door.
The conventional barred door requires that large and often unsightly brackets be mounted on the door frames. Attempts to eliminate this problem have resulted in elongated rods which are wedged between the doorknob and the floor a foot or two away from the door. While these devices are quite strong in resisting door opening from a closed position, they often display a unfortunate tendency to slip on the floor, and the conventional doorknob structure is quite weak and often will not hold together under repeated blows upon the door from the outside.
Other devices have been proposed which wedge a tube or bar diagonally between the inner side of the door and the wall which the inner side of the door confronts when the door is in open position. Often, such device is pivotally fastened to the inner face of the door and is held from slipping on the wall by braces. These devices have the advantage that when not in use they can be rotated to lie flat against the door and not impede its normal use. Typical of the bars wedged between the doorknob and the floor are those disclosed in the following U.S. Pat. Nos.:
______________________________________ U.S Pat. No. Inventor ______________________________________ 4,231,599 Charles Gayman 4,290,636 Richard J. Steele 4,676,536 Harold J. Arbic et al. ______________________________________
Typical of bars wedged between the door and a confronting wall are the disclosures found in the following U.S. Pat. Nos.:
______________________________________ U.S. Pat. No. Inventor ______________________________________ 2,760,806 Burnice Woodard et al. 4,346,926 Frank E. Lucas ______________________________________
Other patents which may be deemed to be of interest in connection with the present application are 4,015,867 to Lars Siden and 4,348,879 to Donald V. Knierim.
Attempts have been made in connection with the devices described above to permit opening of the door by a few inches. For example, U.S. Pat. No. 4,346,926 to Frank E. Lucas provides a stop rod which is too short to engage the wall until the door has been placed slightly ajar. In this embodiment, the door cannot be prevented from opening from its entirely closed position.
With all of the prior art devices, the door cannot be selectively blocked in closed position, then partially opened an inch or two, then moved back to closed position even with an attempted intruder pushing against the door. Conventionally, doors utilizing bars, wedge bars, and the like are provided with a separate device for restricting opening of the door once the restraining device is disengaged. These door opening restricting devices are usually chains of limited length engaged between brackets on the door and on the door frame. Such devices are flimsy, and chain-restricted doors can normally be kicked open with comparative ease.
The above-listed patents are believed to be relevant to the present invention because they were adduced by a prior art search made by an independent searcher, and a copy of each of the above-listed patents is supplied to the Patent and Trademark Office herewith.
The term "prior art" as used herein or in any statement made by or on behalf of applicant means only that any document or thing referred to as prior art bears, directly or inferentially, a date which is earlier than the effective date of this application.
No representation nor admission is made that any of the above-listed documents is part of the prior art in any acceptation of that term, or that no more pertinent information exists.